Synthesis, structure, and reactivity of tetravalent cerium complexes containing oxidizing oxyanion ligands

Abstract

Treatment of [(LOEt)2CeCl2] (LOEt− = [(η5-C5H5)Co{P(O)(OEt)2}3]-) (1) with NaIO4 in water afforded a Ce(IV) periodate complex, 2. Recrystallization of 2 from Et2O afforded orange single crystals that were found to consist of two independent molecules: [(LOEt)2Ce(IO4)2] (2a) and [(LOEt)2Ce(IO4)(H2O)][IO4] (2b). Similarly, treatment of 1 with K2S2O8 in water afforded the Ce(IV) persulfate complex [(LOEt)2Ce(η2-S2O8)] (3). Reaction of [(LOEt)2CeCl2] with I2O5 in MeCN in the presence of a small amount of water led to isolation of the iodate complex [(LOEt)2Ce(IO3)2]⋅H+ICl2− (4). The Ce(IV) periodate and persulfate complexes have been characterized by single-crystal X-ray diffraction. The reduction potentials of the Ce(IV) complexes have been determined by cyclic voltammetry. The Ce(IV) periodate and iodate complexes can oxidize methyl p-tolyl sulfide to sulfoxide.